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#include <QtGui>

#include "CodeEditor.h"
#include "CodeHighlighter.h"


CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
{
    CodeHighlighter *highlighter = new CodeHighlighter(this->document());
    lineNumberArea = new LineNumberArea(this);

    connect(this, SIGNAL(blockCountChanged(int)), this, SLOT(updateLineNumberAreaWidth(int)));
    connect(this, SIGNAL(updateRequest(QRect,int)), this, SLOT(updateLineNumberArea(QRect,int)));
    connect(this, SIGNAL(cursorPositionChanged()), this, SLOT(highlightCurrentLine()));

    updateLineNumberAreaWidth(0);
    highlightCurrentLine();
}



int CodeEditor::lineNumberAreaWidth()
{
    int digits = 1;
    int max = qMax(1, blockCount());
    while (max >= 10)
	{
        max /= 10;
        ++digits;
    }

    int space = 17 + fontMetrics().width(QLatin1Char('9')) * digits;

    return space > 25 ? space : 25;
}



void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
    setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}



void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
    if (dy)
	{
        lineNumberArea->scroll(0, dy);
	}
    else
	{
        lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());
	}

    if (rect.contains(viewport()->rect()))
        updateLineNumberAreaWidth(0);
}



void CodeEditor::resizeEvent(QResizeEvent *e)
{
    QPlainTextEdit::resizeEvent(e);

    QRect cr = contentsRect();
    lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}



void CodeEditor::highlightCurrentLine()
{
    QList<QTextEdit::ExtraSelection> extraSelections;

    if (!isReadOnly())
	{
        QTextEdit::ExtraSelection selection;

        QColor lineColor = QColor(QColor(244, 244, 244)).lighter(160);

        selection.format.setBackground(lineColor);
        selection.format.setProperty(QTextFormat::FullWidthSelection, true);
        selection.cursor = textCursor();
        selection.cursor.clearSelection();
        extraSelections.append(selection);
    }

    setExtraSelections(extraSelections);
}



void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
    QPainter painter(lineNumberArea);
    painter.fillRect(event->rect(), QColor(240, 240, 240));

    QTextBlock block = firstVisibleBlock();
    int blockNumber = block.blockNumber();
    int top = (int) blockBoundingGeometry(block).translated(contentOffset()).top();
    int bottom = top + (int) blockBoundingRect(block).height();

    while (block.isValid() && top <= event->rect().bottom())
	{
        if (block.isVisible() && bottom >= event->rect().top())
		{
            QString number = QString::number(blockNumber + 1);
            painter.setPen(QColor(100, 100, 100));
            painter.drawText(0, top, lineNumberArea->width() - 10, fontMetrics().height(),
                            Qt::AlignRight, number);
        }

        block = block.next();
        top = bottom;
        bottom = top + (int) blockBoundingRect(block).height();
        ++blockNumber;
    }
}